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Easing: Annoying jumps and spikes in graph editor
Hi all,
I’ve had this problem loads so I can only assume this is a common problem. Apologies if this has been addressed in another thread, I’m not sure what to search for.I’m getting some unexpected jumps and movement in the my animations when I use easing on animations.
In this case I’m animating some objects spatially, I move a clip on the stage and add ‘easy ease’ on the end keyframe so that it slows down gradually to the new position.This is how the graph editor looks like for the position parameter
https://twitpic.com/2st2xwOK, all good. But then I add another keyframe at the same position later on in the movie by clicking the diamond next to ‘position’. Same position, but this happens.
https://twitpic.com/2st4sh
What’s with the strange ‘hump’?This creates an annoying and very noticeable kink in my animation, as the object consequently moves on screen. I hate this! I have this all the time and the best I can do is try and surpress it by adding an identical keyframe directly after the ‘hump’ keyframe, and then animate as usual.
what can be done?
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6 Replies
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Hi Dave,
thanks for your quick reply. This is a solution!Any idea why it does this though? To me it seems like rather peculiar behaviour, is it a bug?
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[Kim Taylor] “Any idea why it does this though? To me it seems like rather peculiar behaviour, is it a bug?”
It’s not technically a bug. Everything is working as it should.
The problem is actually not in the temporal interpolation between keyframes (the graph editor) but rather in the spatial interpolation between them. AE defaults to using auto-bezier curves between keyframes, which can cause 2 keyframes that are close to each other to behave strangely.
I recommend that “Default Spatial Interpolation to Linear” should be enabled in your General After Effects preferences. You can then add curves in the motion path with the pen tool later if desired.
The ‘hold’ keyframe technique works as well, but only if the keyframes are at exactly the same position.
Darby Edelen
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Nice, thanks for the explanation all
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That strange hump is bloody irritating, that’s what it is.
I solved it by selecting the guilty keys, right-clicking and picking Keyframe Interpolation. I set Spacial Interpolation to Linear.
I also wagged my finger sternly at the computer, but I’m pretty sure it was the keyframe interpolation wot did it.
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I assume that your spatial interpolation is set to Auto Bezier by default. I also assume, that you’ve altered the in-tangent handle at your second keyframe before adding the third one, otherwise the undesired hump should not have appeared.
Tangents are auto calculated for Auto Bezier, so when you manually alter them, the spatial interpolation is changed to Continuous Bezier. BTW, there’s a bug (at least, in AE 14.2) that even if you ctrl-z and return the handle to its initial position, spatial interpolation will not return to Auto Bezier and will remain Continuous Bezier.
Anyway, when the last keyframe’s spatial interpolation is changed to Continuous Bezier, the out-tangent is set to be equal in absolute value to the in-tangent and opposite to it in direction. So when you later add a keyframe after it with the same value, it so happens that the property value has a non-zero out-acceleration at the Continuous Bezier keyframe, so some motion should happen between the 2nd and the 3rd keyframes – and that’s your hump.
If you set the 2nd keyframe spatial interpolation to Linear or Auto Bezier, you’ll make your layer hold still between the 2nd and the 3rd keyframes. Then you’ll be able to set it back to Continuous Bezier (without messing with out-tangent this time) to alter its in-tangent.
But the common practice it to Toggle Hold Keyframe every time you want a property’s value be constant between two keyframes. Here’s an old CC tutorial on the issue: https://library.creativecow.net/video_page.php?author_folder=rabinowitz_aharon&article_folder=boomerang_1
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